WASHINGTON — President Donald Trump’s job approval rating has declined to the lowest point of his presidency, and nearly half of voters want their vote in the 2018 midterms to be a message for more Democrats in Congress to check Trump and congressional Republicans, according to a new NBC News/Wall Street Journal poll.

Thirty eight percent of Americans say they approve of Trump’s job performance — down five points since September — while 58 percent disapprove.

Trump’s previous low in approval in the national NBC/WSJ poll was 39 percent back in May.

“This is his worst showing of his young presidency so far,” said Democratic pollster Fred Yang of Hart Research Associates, who conducted this survey with Republican pollster Bill McInturff and his team at Public Opinion Strategies.

The drop for Trump has come from independents (who shifted from 41 percent approval in September to 34 percent now), whites (who went from 51 percent to 47 percent) and whites without a college degree (from 58 percent to 51 percent).

“Are we starting to see the fraying of the Trump base … after this week of [Republican] infighting?” Yang asked.

Trump’s job approval rating of 38 percent is the lowest in modern times for a president at this stage of his presidency. The NBC/WSJ poll had George W. Bush at 88 percent, Barack Obama at 51 percent and Bill Clinton at 47 percent in the fall of their first year as president.

In this new survey, Trump also has seen a decline in his personal rating, with 36 percent viewing him positively and 54 percent negatively.

Back in September — when the political headlines were focused more on the president’s handling of the hurricanes that hit Texas and Florida, as well as Trump’s spending deal with congressional Democrats — his score was 39 percent positive, 49 percent negative.

But this current poll, conducted October 23-26, comes on the heels of a tumultuous two weeks in American politics, which included:

Trump charging that his predecessors didn’t make calls to the families of fallen U.S. soldiers;

Trump upsetting the family and friends of Sgt. La David T. Johnson, who was killed in Niger, by allegedly telling them that Johnson “must’ve known what he signed up for”;

Additionally, the NBC/WSJ poll measures some of Trump’s recent actions over the past couple of months. The most popular: By a 48 percent to 27 percent margin, Americans approve of Trump’s handling of the aftermath of Hurricanes Harvey and Irma.

And by a 42 percent-to-37 percent margin, they give a thumbs-up to the president’s handling of the economy.

But Trump is underwater on almost every other issue. Just 35 percent approve of his handling of his role as commander in chief; 34 percent approve of his handling of North Korea; 33 percent approve of his handling of the mass shooting in Las Vegas; and 30 percent approve of Trump’s handling of NFL players protesting during the National Anthem.

At the bottom: 29 percent agree with his handling of the aftermath of Hurricane Maria in Puerto Rico; 27 percent approve of his handling of health care; and 24 percent approve of his handling of the Iran nuclear deal.

Midterm numbers are “a flashing yellow light for Republicans”

Looking ahead to the 2018 midterm elections, which take place a year from now, 48 percent of registered voters in the poll say they prefer a Democratic-controlled Congress, while 41 percent want a Republican-controlled Congress.

That 7-point advantage for Democrats is up one point from September’s NBC/WSJ poll, but it’s smaller than the double digit margins they enjoyed in the 2006 and 2008 cycles, when they picked up a sizable number of congressional seats.

Still, a near-majority of voters, 46 percent, say their vote in November 2018 will be to send a message for more Democrats to serve as a check and balance to Trump and congressional Republicans.

That’s compared with 28 percent who say their vote will be a message for more Republicans to help Trump and congressional Republicans pass their agenda. Another 22 percent said their vote would be a different message than either of those two choices.

And the Republican advantage in GOP-held congressional districts has decreased from +14 in September (52 percent preferring a GOP-controlled Congress versus 38 percent preferring a Democratic-controlled Congress) to +6 in October (47 percent GOP, 41 percent Dem).

“This is a flashing yellow light for Republicans,” said McInturff, the GOP pollster.

The NBC/WSJ poll was conducted Oct. 23-26 of 900 adults, including nearly half of whom were reached by cell phone, and it has an overall margin of error of plus-minus 3.3 percentage points. The margin of error for the 753 registered voters interviewed in the poll is plus-minus 3.6 percentage points.